Control system for fluorescent light fixture

• US 7,414,369 B2
• Filed: 07/26/2005
• Issued: 08/19/2008
• Est. Priority Date: 04/18/2005
• Status: Expired due to Fees

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell World Trade Limited (Marvell Technology Group Limited)
• Inventors: Sutardja, Sehat
• Primary Examiner(s): Dinh; Trinh Vo
• Assistant Examiner(s): DUONG, DIEU HIEN
• Application Number:
  US11/190,025
• Publication Number:
  US 20060232213A1
• Time in Patent Office: 1,120 Days
• Field of Search: 315/46, 315/47, 315/291, 315/209.R, 315/307, 315/308, 315/49
• US Class Current: 315/46
• CPC Class Codes: H05B 41/046 using controlled semiconductor devices
• CPC Class Codes: H05B 41/295 with semiconductor devices and specially adapted for lamps with preheating electrodes, e.g. for fluorescent lamps

Abstract

A control system comprises a switch and a control module that communicates with the switch and that samples a filament resistance of a fluorescent light when the switch is off and that selectively increases current supplied to the fluorescent light above a nominal current value during turn on based on the filament resistance.

Claims

1. A control system comprising:

a switch that switches power to a filament of a fluorescent light and that has first and second states, said second state associated with supplying power to said filament and said first state associated with removing power from said filament; and

a control module that communicates with said switch and that samples a filament resistance of said filament when said switch is in said first state and that selectively increases current supplied to the fluorescent light above a nominal current value when said switch transitions to said second state based on said filament resistance.

2. The control system of claim 1 wherein said control module determines a steady-state filament resistance value when said switch is in said first state and monitors changes in said steady state filament resistance value.

3. The control system of claim 2 further comprising an indicator that communicates with said control module and that indicates an operational state of said fluorescent light.

4. The control system of claim 3 wherein said control module compares changes in said steady state filament resistance value to a predetermined filament resistance change threshold and changes a state of said indicator when said changes in said steady state filament resistance value exceed said predetermined filament resistance change threshold.

5. The control system of claim 4 further comprising an ambient temperature estimator that estimates ambient temperature.

6. The control system of claim 5 wherein said changes in said steady state filament resistance value are adjusted based on said ambient temperature.

7. The control system of claim 5 wherein said ambient temperature estimator includes a temperature sensor.

8. The control system of claim 5 wherein said ambient temperature estimator estimates said ambient temperature based on a filament resistance measured after said fluorescent light has been in said first state for a predetermined period.

9. The control system of claim 3 wherein said control module compares said steady state filament resistance value to a predetermined filament resistance threshold and changes a state of said indicator when said steady state filament resistance value exceeds said predetermined filament resistance threshold.

10. The control system of claim 1 wherein said control module increases at least one of current and voltage to said filament by a first amount above said nominal current level when said switch turns on based on a stored filament resistance value of said filament that is stored before said switch turns on.

11. The control system of claim 10 wherein said control module determines and stores a steady-state filament resistance value when said switch is in said first state and wherein said control module increases at least one of current and voltage to said filament by a first amount above said nominal level when said switch transitions to said second state based on a difference between a stored filament resistance value that is stored before said switch transitions to said second state and said stored steady state filament resistance value.

12. The control system of claim 1 further comprising:

a ballast module comprising

an electrolytic capacitance element; and

a first temperature sensor that senses a first temperature of said electrolytic capacitance element, wherein said control module communicates with said first temperature sensor and adjusts power output to the fluorescent light when said first temperature exceeds a predetermined threshold.

13. The control system of claim 12 wherein said control module modulates said power output based on said first temperature.

14. The control system of claim 12 further comprising a rectifier module having an input that selectively communicates with a voltage source, wherein said electrolytic capacitance element and said control module communicate with an output of said rectifier module.

15. The control system of claim 12 further comprising:

a electrical component; and

a second temperature sensor that senses a second temperature of said first electrical component, wherein said control module communicates with said second temperature sensor and adjusts power output to the fluorescent light when said second temperature exceeds a predetermined threshold.

16. The control system of claim 15 further comprising a rectifier module having an input that selectively communicates with a voltage source, wherein said control module communicate with an output of said rectifier module.

17. The control system of claim 1 wherein said control module reacts based on state of said switch.

18. The control system of claim 1 wherein said switch receives power from a power source.

19. The control system of claim 1 wherein said switch is coupled between a power source and a rectifier.

20. The control system of claim 1 wherein said switch is coupled between a power source and a control module.

21. The control system of claim 1 wherein said filament is OFF when said switch is in said first state.

22. The control system of claim 1 wherein said filament receives a power signal when in an ON state and does not receive a power signal when in an OFF state.

23. A method for operating a fluorescent light, comprising:

selectively switching power to a filament of the fluorescent light between first and second states, said second state associated with supplying power to said filament and said first state associated with removing power from said filament;

sampling a filament resistance of said filament when said fluorescent light is in said first state; and

selectively increasing current supplied to the fluorescent light above a nominal current value when transitioning to said second state based on said filament resistance.

24. The method of claim 23 further comprising:

determining a steady-state filament resistance value when said fluorescent light is off; and

monitoring changes in said steady state filament resistance value.

25. The method of claim 24 further comprising indicating an operational state of said fluorescent light based on said filament resistance.

26. The method of claim 25 further comprising:

comparing changes in said steady state filament resistance value to a predetermined filament resistance change threshold; and

changing a state of an indicator when said changes in said steady state filament resistance value exceed said predetermined filament resistance change threshold.

27. The method of claim 26 further comprising estimating ambient temperature.

28. The method of claim 27 further comprising adjusting changes in said steady state filament resistance value based on said ambient temperature.

29. The method of claim 27 further comprising estimating said ambient temperature based on a filament resistance measured after said fluorescent light has been in an off state for a predetermined period.

30. The method of claim 24 further comprising:

comparing said steady state filament resistance value to a predetermined filament resistance threshold; and

changing a state of said indicator when said steady state filament resistance value exceeds said predetermined filament resistance threshold.

31. The method of claim 23 further comprising increasing at least one of current and voltage to said filament by a first amount above said nominal current level when said fluorescent light turns on based on a stored filament resistance value of said filament that is stored before said fluorescent light turns on.

32. The method of claim 31 further comprising determining and storing a steady-state filament resistance value when said fluorescent light is off and wherein said control module increases at least one of current and voltage to said filament by a first amount above said nominal level when said fluorescent light is turned on based on a difference between a stored filament resistance value that is stored before said switch turns on and said stored steady state filament resistance value.

33. The method of claim 23 further comprising:

sensing a temperature of an electrolytic capacitance element; and

adjusting power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

34. The method of claim 33 further comprising modulating said power output based on said sensed temperature.

35. The method of claim 23 further comprising:

sensing a temperature of a first electrical component; and

adjusting power output to the fluorescent light when said sensed temperature exceeds a predetermined threshold.

36. A control system comprising:

lighting means having an ON state and an OFF state;

and control means that communicates with said lighting means for sampling a filament resistance of said lighting means when said lighting means is in said OFF state and for selectively increasing current supplied to said lighting means above a nominal current value when said lighting means transitions to said ON state based on said filament resistance,

wherein said control means determines a steady-state filament resistance value when said switch means is in said OFF state and monitors changes in said steady state filament resistance value.

37. The control system of claim 36 further comprising Indicating means that communicates with said control means for indicating an operational state of said fluorescent light.

38. The control system of claim 37 wherein said control means compares changes in said steady state filament resistance value to a predetermined filament resistance change threshold and changes a state of said indicating means when said changes in said steady state filament resistance value exceed said predetermined filament resistance change threshold.

39. The control system of claim 37 wherein said control means compares said steady state filament resistance value to a predetermined filament resistance threshold and changes a state of said indicating means when said steady state filament resistance value exceeds said predetermined filament resistance threshold.

40. The control system of claim 37 further comprising ambient temperature estimating means for estimating ambient temperature.

41. The control system of claim 40 wherein said changes in said steady state filament resistance value are adjusted based on said ambient temperature.

42. The control system of claim 40 wherein said ambient temperature estimating means includes temperature sensing means for sensing temperature.

43. The control system of claim 40 wherein said ambient temperature estimating means estimates said ambient temperature based on a filament resistance measured after said fluorescent light has been in said OFF state for a predetermined period.

44. The control system of claim 36 further comprising switch means for switching, wherein said control means increases at least one of current and voltage to said filament by a first amount above said nominal current level when said switch means transitions to an ON state based on a stored filament resistance value of said filament that is stored before said switch means transitions to said ON state.

45. The control system of claim 44 wherein said control means determines and stores a steady-state filament resistance value when said switch means is in an OFF state and wherein said control means increases at least one of current and voltage to said filament by a first amount above said nominal level when said switch means transitions to said ON state based on a difference between a stored filament resistance value that is stored before said switch means transitions to said ON state and said stored steady state filament resistance value.

46. The control system of claim 36 further comprising:

electrolytic capacitance means for providing capacitance;

first temperature sensing means for sensing a first temperature of said electrolytic capacitance means, wherein said control means communicates with said first temperature sensing means and adjusts power output to the fluorescent light when said first temperature exceeds a predetermined threshold.

47. The control system of claim 46 wherein said control means modulates said power output based on said first temperature.

48. The control system of claim 46 further comprising rectifier means for rectifying and having an input that selectively communicates with a voltage source, wherein said electrolytic capacitance means and said control means communicate with an output of said rectifier means.

49. The control system of claim 46 further comprising:

a electrical component; and

second temperature sensing means for sensing a second temperature of said electrical component, wherein said control means communicates with said second temperature sensing means and adjusts power output to the fluorescent light when said second temperature exceeds a predetermined threshold.

50. The control system of claim 49 further comprising rectifier means for rectifying and having an input that selectively communicates with a voltage source, wherein said control means communicates with an output of said rectifier means.

51. A control system comprising:

a switch that enables activation of a fluorescent light;

a temperature sensor that generates a temperature signal; and

a control module that samples a filament resistance of said fluorescent light when said switch is in a first state, that selectively increases current supplied to the fluorescent light above a nominal current value when said switch transitions to a second state, and that adjusts current supplied to said filament based on said filament resistance and said temperature signal.